MM5/CALMET/CALPUFF数值模式在关中地区SO_2环境空气总量控制中的应用

Application of the MM5/CALMET/CALPUFF system to Guanzhong basin area for SO_2 emission control

利用中尺度气象数值模式MM5、边界层风温场诊断数值模式CALMET和污染物扩散多源数值模式CALPUFF,模拟和预测了关中地区2007年逐时气象要素场和SO2的质量浓度分布。SO2质量浓度预测结果与监测结果的对比分析表明,年均质量浓度的预测与监测值比较接近,日均质量浓度的预测与监测值的时间变化趋势基本一致。污染物扩散轴线与主导风去向一致。西安、咸阳和铜川污染物的扩散主要沿东北、西南方向,宝鸡、商洛主要沿西北、东南方向,渭南市沿着秦岭北麓向东西方向扩散,表现出关中特有地形和气象条件对污染物扩散的影响。在现状SO2排放源和不考虑城乡界线的条件下,以各市SO2年均质量浓度最大值点作为控制点,年均质量浓度的二级标准为判断条件,采用等比例消减原则测算关中地区SO2的环境空气总量约60万t/a,西安、咸阳、宝鸡、渭南、铜川、洛南分别约9万t/a、11万t/a、7万t/a、29万t/a、2万t/a、2万t/a;在考虑城乡界线的情景下,关中地区SO2允许排放总量约31万t。

This paper seeks to analyze the corresponding contributions of major sulphuric dioxide （SO2） emissions to the total air-quality in- fluence in hoping to reduce the pollution in Guanzhong Basin Area （GZBA）. In proceeding with our study, we have attempted to adopt the coupling of the MM5/CALMET system with the CALPUFF model, the multi-layer, non-steady-state puff dispersion model, which takes the major power plants and plane sources and all the rest in the GZR 2007, into account. We have also analyzed the observation data and simulation results gained from the 18 stations of Gaanzhong Environ- mental Protection Departments. In addition, we have also defined the Urban （in-zone） and Rural （out-zone） stations in order to examine the SO2 contribution of different emission sources in different regions of the area. The survey and statistics results show that the annual concentration assessment and monitoring values, the time changing trend of the predicted and monitoring Daily average density are basi- cally in mutual conformity. The same is basically true with the axis of the pollutant dispersion and the main wind direction, with Xi＇ an, Xi- anyang and Tongchuan mainly taking the northeast and southwest di- rection, while Baoji and Shangluo mainly following the northwest and southeast direction, however, Weinan and Qinling mountainous areas tend to take the east and west directions. Our survey also shows that the air pollution influences the contaminants of the special terrain and meteorolocal conditions. Specifically speaking, we have taken the maximum points of the SO2 annual concentration as the principal con- trol points, while the secondary standard of annual concentration is used to judge the pollution situation by using the equal proportion-re- ducing method. If ignoring the difference of the boundaries between the urban and rural areas, the total SO2 emissions of the entire area put to- gether have been worked out at about 600 000 tons/year in the GZR, with about 90 000 tons/year in Xian district, about 110 000 tons/year in Xianyang, about 70 000 tons/year in Baoji, about 290 000 tons/year in Weinan, about 20 000 tons/year in Tongchuan, and about 20 000 tons/year in Shangluo. If the pollution situation in the border areas between the urban and rural classification, the total SO2 emission volume can be worked out about 31 0000 tones/year in the entire GZA.